Proposition REF  also implies that the set of pivot columns in Algorithm  and the set of columns indexed by \(\mathrm {def}(\mu )\)  are disjoint. This gives rise to a natural dual approach, in which one skips over, clears, or deletes columns indexed by \(\mathrm {def}(\mu )\) . This idea was developed into a formal acceleration technique in [1]}; in experiments, the technique improved time and memory use substantially.
